Dialysis system and methods

ABSTRACT

Dialysis systems and methods are described which can include a number of features. The dialysis systems described can be to provide dialysis therapy to a patient in the comfort of their own home. The dialysis system can be configured to prepare purified water from a tap water source in real-time that is used for creating a dialysate solution. The dialysis systems described also include features that make it easy for a patient to self-administer therapy. For example, the dialysis systems include disposable cartridge and patient tubing sets that are easily installed on the dialysis system and automatically align the tubing set, sensors, venous drip chamber, and other features with the corresponding components on the dialysis system. Methods of use are also provided, including automated priming sequences, blood return sequences, and dynamic balancing methods for controlling a rate of fluid transfer during different types of dialysis, including hemodialysis, ultrafiltration, and hemodiafiltration.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of pending U.S. application Ser. No.14/699,875, filed Apr. 29, 2015, which application claims the benefit ofU.S. Provisional Application No. 61/985,779, filed Apr. 29, 2014, titled“Air Removal in Modular Home Dialysis System”, and also claims thebenefit of U.S. Provisional Application No. 62/127,155, filed Mar. 2,2015, titled “Dialysis System”, both of which are incorporated herein byreference.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference to the same extent as if eachindividual publication or patent application was specifically andindividually indicated to be incorporated by reference.

FIELD

This disclosure generally relates to dialysis systems. Morespecifically, this disclosure relates to dialysis systems that includemany features that reduce the need for technician involvement in thepreparation and administration of dialysis treatment.

BACKGROUND

There are, at present, hundreds of thousands of patients in the UnitedStates with end-stage renal disease. Most of those require dialysis tosurvive. Many patients receive dialysis treatment at a dialysis center,which can place a demanding, restrictive and tiring schedule on apatient. Patients who receive in-center dialysis typically must travelto the center at least three times a week and sit in a chair for 3 to 4hours each time while toxins and excess fluids are filtered from theirblood. After the treatment, the patient must wait for the needle site tostop bleeding and blood pressure to return to normal, which requireseven more time taken away from other, more fulfilling activities intheir daily lives. Moreover, in-center patients must follow anuncompromising schedule as a typical center treats three to five shiftsof patients in the course of a day. As a result, many people who dialyzethree times a week complain of feeling exhausted for at least a fewhours after a session.

Many dialysis systems on the market require significant input andattention from technicians prior to, during, and after the dialysistherapy. Before therapy, the technicians are often required to manuallyinstall patient blood tubing sets onto the dialysis system, connect thetubing sets to the patient, and to the dialyzer, and manually prime thetubing sets to remove air from the tubing set before therapy. Duringtherapy, the technicians are typically required to monitor venouspressure and fluid levels, and administer boluses of saline and/orheparin to the patient. After therapy, the technicians are oftenrequired to return blood in the tubing set to the patient and drain thedialysis system. The inefficiencies of most dialysis systems and theneed for significant technician involvement in the process make it evenmore difficult for patients to receive dialysis therapy away from largetreatment centers.

Given the demanding nature of in-center dialysis, many patients haveturned to home dialysis as an option. Home dialysis provides the patientwith scheduling flexibility as it permits the patient to choosetreatment times to fit other activities, such as going to work or caringfor a family member. Unfortunately, current dialysis systems aregenerally unsuitable for use in a patient's home. One reason for this isthat current systems are too large and bulky to fit within a typicalhome. Current dialysis systems are also energy-inefficient in that theyuse large amounts of energy to heat large amounts of water for properuse. Although some home dialysis systems are available, they generallyuse complex flow-balancing technology that is relatively expensive tomanufacture and most systems are designed with a system of solenoidvalves that create high noise levels. As a result, most dialysistreatments are performed at dialysis centers.

SUMMARY OF THE DISCLOSURE

A method of achieving dynamic balancing with a dialysis system isprovided, comprising operating a blood pump to move a flow of blood froma patient through a patient tubing set and a blood-side of a dialyzer,operating a first dialysate pump and a second dialysate pump to move aflow of dialysate through a dialysate-side of the dialyzer, bypassingthe flow of dialysate through the dialysate-side of the dialyzer, andwhile the flow of dialysate through the dialysate-side of the dialyzeris bypassed, measuring a dialysate pressure between the first dialysatepump and the second dialysate pump, and adjusting a pump speed of thesecond dialysate pump until the measured dialysate pressure stabilizes.

In some embodiments, the method further comprises resuming the flow ofdialysate through the dialysate-side of the dialyzer.

In other embodiments, no fluid passes from the blood-side of thedialyzer to the dialysate-side of the dialyzer when the flow ofdialysate resumes through the dialysate-side of the dialyzer.

A method of achieving dynamic balancing with a dialysis system is alsoprovided, comprising operating a blood pump to move a flow of blood froma patient through a patient tubing set and a blood-side of a dialyzer,measuring a venous pressure of the patient, operating a first dialysatepump and a second dialysate pump to move a flow of dialysate through adialysate-side of the dialyzer, preventing a flow of dialysate frompassing through the dialysate-side of the dialyzer, while the flow ofdialysate through the dialysate-side of the dialyzer is prevented,measuring a dialysate pressure between the first dialysate pump and thesecond dialysate pump, and adjusting a pump speed of the seconddialysate pump until the measured dialysate pressure stabilizes,allowing the flow of dialysate to pass through the dialysate-side of thedialyzer, and adjusting a pump speed of the second dialysate pump tocreate a flow imbalance between the first and second dialysate pumpsthat results in a flow of fluid between the blood-side of the dialyzerand the dialysate-side of the dialyzer to equalize the flow imbalance.

In one embodiment, the flow of fluid travels from the blood-side of thedialyzer to the dialysate-side of the dialyzer.

In another embodiment, the flow of fluid travels from the dialysate-sideof the dialyzer to the blood-side of the dialyzer.

In some embodiments, the method further comprises further adjusting thepump speed of the second dialysate pump to calibrate for a pressure lossbetween the blood-side of the dialyzer and the dialysate-side of thedialyzer.

In other embodiments, the method further comprises repeating thepreventing, measuring, and adjusting steps if the measured venouspressure changes by a predetermined threshold.

In one embodiment, the predetermined threshold comprises more than 30mmHg.

A dialysis system is provided, comprising a blood pump configured tomove a flow of blood from a patient through a patient tubing set and ablood-side of a dialyzer, a venous pressure sensor configured to measurea venous pressure of the patient, a first pump and a second pumpconfigured to control the flow of dialysate through a dialysate-side ofthe dialyzer, one or more valves configured to bypass the dialysate-sideof the dialyzer to prevent the flow of dialysate from passing throughthe dialysate-side of the dialyzer, a dialysate pressure sensor disposedbetween the first and second pumps and configured to measure a dialysatepressure when the dialysate-side of the dialyzer is bypassed, and anelectronic controller operatively coupled to the blood pump, the venouspressure sensor, the first and second pumps, the one or more valves, andthe dialysate pressure sensor, the electronic controller configured toadjust a pump speed of the first and second pumps to create a flowimbalance between the first and second pumps that results in a flow offluid between the blood-side of the dialyzer and the dialysate-side ofthe dialyzer to equalize the flow imbalance.

A dialysis system is provided, comprising a dialyzer comprising ablood-side and a dialysate-side, a blood circuit coupled to theblood-side of the dialyzer and further comprising a venous line adaptedto be connected to an venous connection site of a patient and anarterial line adapted to be connected to an arterial connection site ofthe patient, a blood pump coupled to the blood circuit and configured tomove blood from the patient, through the arterial line, through theblood-side of the dialyzer, and through the venous line back into thepatient, a venous pressure sensor coupled to the blood circuit andconfigured to measure a venous pressure of the patient, a dialysatecircuit coupled to the dialysate-side of the dialyzer and furthercomprising a dialysate line coupled to a dialysate source, an actuatorcoupled to the dialysate circuit, the actuator comprising a firstconfiguration in which dialysate moves through the dialysate-side of thedialyzer and a second configuration in which dialysate is prevented frommoving through the dialysate-side of the dialyzer, a first dialysatepump and a second dialysate pump coupled to the dialysate circuit andconfigured to move dialysate from the dialysate source, through thedialysate line, and through the dialysate-side of the dialyzer when theactuator is in the first configuration, a dialysate pressure sensorcoupled to the dialysate circuit and configured to measure a pressure ofthe dialysate between the first dialysate pump and the second dialysatepump, an electronic controller operatively coupled to the blood pump,the venous pressure sensor, the dialysate pressure sensor, the actuator,the first dialysate pump, and the second dialysate pump, the electroniccontroller being configured to achieve dynamic balancing of fluid flowacross the dialyzer during dialysis therapy by performing the steps ofadjusting a pump speed of the first dialysate pump to move a flow ofdialysate through the dialysate-side of the dialyzer, controlling theactuator to prevent the flow of dialysate from moving through thedialysate-side of the dialyzer, receiving the measured dialysatepressure from the dialysate pressure sensor, and adjusting a pump speedof the second dialysate pump until the measured dialysate pressurestabilizes, controlling the actuator to allow the flow of dialysate tomove through the dialysate-side of the dialyzer, and adjusting a pumpspeed of the second dialysate pump to create a flow imbalance betweenthe first and second dialysate pumps that results in a flow of fluidbetween the blood-side of the dialyzer and the dialysate-side of thedialyzer to equalize the flow imbalance.

In some embodiments, the electronic controller is configured to receivethe measured venous pressure from the venous pressure sensor, and isconfigured to repeat the controlling, receiving, and adjusting steps ifthe measured venous pressure changes by a predetermined threshold.

A method of connecting a disposable cartridge and tubing set to adialysis system is provided, comprising the steps of positioningalignment features of the disposable cartridge and tubing set next toalignment features of the dialysis system, and mounting the disposablecartridge and tubing set onto the dialysis system to acoustically couplea venous drip chamber of the disposable cartridge and tubing set withone or more fluid level sensors of the dialysis system.

In some embodiments, the method further comprises measuring a fluidlevel within the venous drip chamber with the one or more fluid levelsensors.

A disposable cartridge adapted to be mounted onto a dialysis system isprovided, comprising a frame having a plurality of alignment featuresconfigured to removably mate with corresponding alignment features onthe dialysis system, a tubing set disposed in the frame, and a venousdrip chamber disposed in the frame and connected to the tubing set, thevenous drip chamber being positioned within the frame such that it isacoustically coupled to one or more fluid level sensors of the dialysissystem when the frame is mounted onto the dialysis system.

A method of priming a tubing set and a dialyzer of a dialysis system isalso provided, comprising the steps of operating a blood pump of thedialysis system in a first operating mode to move saline from a salinesource into the tubing set and through a blood-side of the dialyzer in afirst direction to remove air from the tubing set and the blood-side ofthe dialyzer, and operating the blood pump in a second operating mode tomove at least a portion of the saline through the blood-side of thedialyzer in a second direction opposite to the first direction and outof the tubing set.

In some embodiments, the method further comprises monitoring a fluidlevel of the saline in a venous drip chamber of the tubing set, andstopping operation of the blood pump in the first operating mode whenthe fluid level in the venous drip chamber stabilizes or when air nolonger circulates through the tubing set.

In one embodiment, operating the blood pump in the first operating modefurther comprises moving at least a portion of the saline into a venousdrip chamber of the tubing set before moving the saline through theblood-side of the dialyzer.

In another embodiment, operating the blood pump in the second operatingmode further comprises moving at least a portion of the saline throughthe blood-side of the dialyzer before moving the saline through a venousdrip chamber of the tubing set.

In some embodiments, the method further comprises operating a dialysatepump to move dialysate from a dialysate source through a dialysate-sideof the dialyzer in the first direction to remove air from thedialysate-side of the dialyzer.

In some embodiments, air is removed from the dialysate-side of thedialyzer without physically manipulating an orientation of the dialyzer.

In other embodiments, air is removed from the dialysate-side of thedialyzer without flipping an orientation of the dialyzer.

In some embodiments, the method further comprises opening one or morevalves of the dialysis system with an electronic control to allow thesaline to move from the saline source into the tubing set.

In one embodiment, the operating the blood pump steps further compriseoperating the blood pump with an electronic controller of the dialysissystem.

In other embodiments, the saline is moved out of the tubing set througha union joint that attaches a venous line of the tubing set to anarterial line of the tubing set.

In some embodiments, a predetermined volume of saline is moved throughthe union joint before the dialysis therapy can begin.

A method of returning blood in a patient tubing set of a dialysisdelivery system to a patient after a dialysis treatment is provided,comprising activating a blood pump coupled to the patient tubing set todraw saline into the patient tubing set and push blood back into thepatient, tracking the number of revolutions of the blood pump todetermine the amount of saline drawn into the patient tubing set, andde-activating the blood pump when a predetermined volume of saline isdrawn into the patient tubing set.

In some embodiments, the predetermined volume comprises 300-500 ml.

In some embodiments, the method further comprises opening one or morepinch valves of the dialysis delivery system to create a pathway betweena saline source and the tubing set.

In additional embodiments, the method further comprises opening one ormore pinch valves to create the pathway between the saline source andthe tubing set at or adjacent to a patient arterial access site.

In some embodiments, blood is pushed back into the patient through apatient venous access site.

A method of draining fluid out of a dialyzer of a dialysis system aftera dialysis treatment is provided, comprising closing a venous line of apatient tubing set of the dialysis system, and operating a pump coupledto the patient tubing set to pull fluid from a dialysate-side of thedialyzer into a blood-side of the dialyzer and out of the dialyzer intoa waste container.

In some embodiments, the waste container comprises a saline bag.

In other embodiments, the fluid is pulled through microtube walls of thedialyzer to move the fluid from the dialysate-side of the dialyzer tothe blood-side of the dialyzer.

In additional embodiments, the fluid is pulled from the dialyzer againstgravity.

A method of controlling a fluid level in a venous drip chamber of adialysis system during therapy is provided, comprising the steps ofgenerating a flow of blood through a patient tubing set and the venousdrip chamber, monitoring a fluid level of the blood in the venous dripchamber with first and second sensors, automatically pumping or ventingair out of the venous drip chamber if the fluid level dips below thefirst sensor, and automatically pumping air into the venous drip chamberif the fluid level rises above the second sensor.

A method of controlling a fluid level in a venous drip chamber of adialysis system during therapy is provided, comprising the steps ofgenerating a flow of blood through a patient tubing set and the venousdrip chamber, monitoring a fluid level of the blood in the venous dripchamber with a sensor, automatically pumping or venting air out of thevenous drip chamber if the sensor detects the fluid level dropping belowa lower fluid level threshold, automatically pumping air into the venousdrip chamber if the sensor detects the fluid level rising above an upperfluid level threshold.

A method of controlling a fluid level in a venous drip chamber of adialysis system during therapy is provided, comprising the steps ofgenerating a flow of blood through a patient tubing set and the venousdrip chamber, monitoring a fluid level of the blood in the venous dripchamber with first and second sensors, and automatically maintaining thefluid level of the blood in the venous drip chamber by pumping orventing air out of the venous drip chamber if the first sensor detectsthe fluid level dropping below a lower threshold and pumping air intothe venous drip chamber if the second sensor detects the fluid levelrising above an upper threshold.

A dialysis system is provided, comprising a venous drip chamberconfigured to remove air from blood flowing therethrough, at least onesensor configured to monitor a fluid level of blood in the venous dripchamber, a pump coupled to the venous drip chamber and configured topump air into or out of the venous drip chamber, and an electroniccontroller in communication with the at least one sensor and the pump,the electronic controller configured to automatically control the pumpto maintain the fluid level of the blood in the venous drip chamber bypumping air out of the venous drip chamber with the pump when the atleast one sensor detects the fluid level dropping below a firstthreshold and pumping air into the venous drip chamber with the pumpwhen the at least one sensor detects the fluid level rising above asecond threshold.

A disposable cartridge adapted to be inserted into a dialysis system foruse in dialysis therapy is provided, comprising an organizer having aplurality of aligning holes configured to mate with alignment pegs onthe dialysis delivery system, a tubing set disposed in the organizer,the tubing set comprising, an arterial line portion configured to drawblood from a patient, a venous line portion configured to return bloodto the patient, a blood pump portion configured to interface with ablood pump of the dialysis delivery system, a first dialyzer portionconfigured to carry blood to a dialyzer of the dialysis delivery system,a second dialyzer portion configured to return blood from the dialyzer,first and second saline lines configured to couple a saline source tothe tubing set, a venous drip chamber disposed in the organizer andconfigured to remove air from blood entering the venous drip chamber,the venous drip chamber comprising, first and second ports disposed on alower portion of the venous drip chamber, the first port being coupledto the venous line portion of the tubing set, the second port beingcoupled to the arterial line portion of the tubing set.

In some embodiments, the disposable cartridge further comprises aheparin line configured to couple a heparin source to the tubing set.

In one embodiment, the heparin line is coupled to a third port disposedon an upper portion of the venous drip chamber.

In another embodiment, the heparin line is coupled to the venous dripchamber at a non-pulsatile location to prevent back streaming of bloodinto the heparin line during therapy.

In some embodiments, the non-pulsatile location comprises an air gap inthe venous drip chamber.

In other embodiments, the first saline line is attached to the tubingset at a proximal end of the blood pump portion of the tubing set.

In additional embodiments, the second saline line is attached to thetubing set near a proximal end of the arterial line portion of thetubing set.

In some embodiments, the disposable cartridge further comprises anarterial pressure pod disposed along the arterial line portion of thetubing set and configured to mate with an arterial pressure sensor ofthe dialysis delivery system.

In additional embodiments, the disposable cartridge further comprises avenous transducer connection coupled to the venous drip chamber andconfigured to mate with a venous pressure sensor of the dialysisdelivery system.

A dialysis system is provided, comprising a housing, a waterpurification system disposed in the housing and configured to preparewater for use in dialysis therapy in real-time using an available watersource, a dialysis delivery system disposed in the housing configured toprepare dialysate for dialysis therapy, a dialyzer disposed on or in thehousing, a front panel disposed on the housing; the front panelcomprising, a plurality of alignment features, a venous level sensor, ablood pump, a plurality of pinch valves, an organizer configured to bemounted to the front panel, the organizer including a plurality ofmounting features configured to mate with the plurality of alignmentfeatures, the organizer comprising, a tubing set disposed in theorganizer, the tubing set comprising, an arterial line portionconfigured to draw blood from a patient, a venous line portionconfigured to return blood to the patient, a blood pump portionconfigured to interface with the blood pump, a first dialyzer portionconfigured to carry blood to the dialyzer, a second dialyzer portionconfigured to return blood from the dialyzer, first and second salinelines configured to couple a saline source to the tubing set, a venousdrip chamber disposed in the organizer and configured to remove air fromblood entering the venous drip chamber, the venous drip chambercomprising, first and second ports disposed on a lower portion of thevenous drip chamber, the first port being coupled to the venous lineportion of the tubing set, the second port being coupled to the arterialline portion of the tubing set, wherein mounting the organizer to thefront panel automatically couples the blood pump portion of the tubingset to the blood pump and the venous drip chamber to the venous levelsensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the invention are set forth with particularity inthe claims that follow. A better understanding of the features andadvantages of the present invention will be obtained by reference to thefollowing detailed description that sets forth illustrative embodiments,in which the principles of the invention are utilized, and theaccompanying drawings of which:

FIG. 1 shows one embodiment of a dialysis system.

FIG. 2 illustrates one embodiment of a water purification system of thedialysis system.

FIG. 3 illustrates one embodiment of a dialysis delivery system of thedialysis system.

FIG. 4 shows one example of a front panel of the dialysis deliverysystem.

FIGS. 5 and 6 illustrate one embodiment of a cartridge including atubing set attached to an organizer.

FIG. 7 shows a flow diagram of the water purification system containedwithin the dialysis system.

FIG. 8 is a schematic diagram showing a water supply subsystem, afiltration subsystem, a pre-heating subsystem, an RO filtrationsubsystem, and a pasteurization subsystem of the water purificationsystem of the dialysis system.

FIG. 9 shows the features of the water supply subsystem of the waterpurification system.

FIG. 10 shows one embodiment of a filtration subsystem of the waterpurification system.

FIG. 11 shows one embodiment of a pre-heating subsystem of the waterpurification system.

FIG. 12 shows one embodiment of a RO filtration subsystem of the waterpurification system.

FIG. 13 illustrates one embodiment of a pasteurization subsystem of thewater preparation system.

FIG. 14 illustrates a schematic of a mixing subsystem of the dialysisdelivery system.

FIG. 15 shows one embodiment of a mixing chamber.

FIG. 16 illustrates an ultrafiltration subsystem of the dialysisdelivery system which can receive the prepared dialysate from the mixingsubsystem.

FIG. 17 shows a schematic diagram illustrating the flow of salinethrough tubing set during blood return to the user.

FIG. 18 shows one embodiment of a union joint adapted to connect venousand arterial lines of a patient tubing set during a priming sequence.

DETAILED DESCRIPTION

This disclosure describes systems, devices, and methods related todialysis therapy, including a dialysis system that is simple to use andincludes automated features that eliminate or reduce the need fortechnician involvement during dialysis therapy. In some embodiments, thedialysis system can be a home dialysis system. Embodiments of thedialysis system can include various features that automate and improvethe performance, efficiency, and safety of dialysis therapy.

In some embodiments, a dialysis system is described that can provideacute and chronic dialysis therapy to users. The system can include awater purification system configured to prepare water for use indialysis therapy in real-time using available water sources, and adialysis delivery system configured to prepare the dialysate fordialysis therapy. The dialysis system can include a disposable cartridgeand tubing set for connecting to the user during dialysis therapy toretrieve and deliver blood from the user.

FIG. 1 illustrates one embodiment of a dialysis system 100 configured toprovide dialysis treatment to a user in either a clinical ornon-clinical setting, such as the user's home. The dialysis system 100can comprise a water purification system 102 and a dialysis deliverysystem 104 disposed within a housing 106. The water purification system102 can be configured to purify a water source in real-time for dialysistherapy. For example, the water purification system can be connected toa residential water source (e.g., tap water) and prepare pasteurizedwater in real-time. The pasteurized water can then be used for dialysistherapy (e.g., with the dialysis delivery system) without the need toheat and cool large batched quantities of water typically associatedwith water purification methodologies.

Dialysis system 100 can also include a cartridge 120 which can beremovably coupled to the housing 106 of the system. The cartridge caninclude a patient tubing set attached to an organizer, which will bedescribed in more detail below. The cartridge and tubing set, which canbe sterile, disposable, one-time use components, are configured toconnect to the dialysis system prior to therapy. This connectioncorrectly aligns corresponding components between the cartridge, tubingset, and dialysis system prior to dialysis therapy. For example, thetubing set is automatically associated with one or more pumps (e.g.,peristaltic pumps), clamps and sensors for drawing and pumping theuser's blood through the tubing set when the cartridge is coupled to thedialysis system. The tubing set can also be associated with a salinesource of the dialysis system for automated priming and air removalprior to therapy. In some embodiments, the cartridge and tubing set canbe connected to a dialyzer 126 of the dialysis system. In otherembodiments, the cartridge and tubing set can include a built-indialyzer that is pre-attached to the tubing set. A user or patient caninteract with the dialysis system via a user interface 113 including adisplay.

FIGS. 2-3 illustrate the water purification system 102 and the dialysisdelivery system 104, respectively, of one embodiment of the dialysissystem 100. The two systems are illustrated and described separately forease of explanation, but it should be understood that both systems canbe included in a single housing 106 of the dialysis system. FIG. 2illustrates one embodiment of the water purification system 102contained within housing 106 that can include a front door 105 (shown inthe open position). The front door 105 can provide access to featuresassociated with the water purification system such as one or morefilters, including sediment filter(s) 108, carbon filter(s) 110, andreverse osmosis (RO) filter(s) 112. The filters can be configured toassist in purifying water from a water source (such as tap water) influid communication with the water purification system 102. The waterpurification system can further include heating and cooling elements,including heat exchangers, configured to pasteurize and control fluidtemperatures in the system, as will be described in more detail below.The system can optionally include a chlorine sample port 195 to providesamples of the fluid for measuring chlorine content.

In FIG. 3, the dialysis delivery system 104 contained within housing 106can include an upper lid 109 and front door 111, both shown in the openposition. The upper lid 109 can open to allow access to various featuresof the dialysis system, such as user interface 113 (e.g., a computingdevice including an electronic controller and a display such as a touchscreen) and dialysate containers 117. Front door 111 can open and closeto allow access to front panel 210, which can include a variety offeatures configured to interact with cartridge 120 and its associatedtubing set, including alignment and attachment features configured tocouple the cartridge 120 to the dialysis system 100. Dialyzer 126 can bemounted in front door 111 or on the front panel, and can include linesor ports connecting the dialyzer to the prepared dialysate as well as tothe tubing set of the cartridge.

In some embodiments, the dialysis system 100 can also include a bloodpressure cuff to provide for real-time monitoring of user bloodpressure. The system (i.e., the electronic controller of the system) canbe configured to monitor the blood pressure of the user during dialysistherapy. If the blood pressure of the user drops below a threshold value(e.g., a blood pressure threshold that indicates the user is hypotonic),the system can alert the user with a low blood pressure alarm and thedialysis therapy can be stopped. In the event that the user ignores aconfigurable number of low blood pressure alarms from the system, thesystem can be configured to automatically stop the dialysis therapy, atwhich point the system can inform the user that return of the user'sblood (the blood that remains in the tubing set and dialyzer) back tothe user's body is necessary. For example, the system can bepre-programmed to automatically stop therapy if the user ignores threelow blood pressure alarms. In other embodiments, the system can give theuser a bolus of saline to bring user fluid levels back up beforeresuming dialysis therapy. The amount of saline delivered to the patientcan be tracked and accounted for during ultrafiltration fluid removal.

The dialysis delivery system 104 of FIG. 3 can be configured toautomatically prepare dialysate fluid with purified water supplied bythe water purification system 102 of FIG. 2. Furthermore, the dialysisdelivery system can de-aerate the purified water, and proportion and mixin acid and bicarbonate concentrates from dialysate containers 117. Theresulting dialysate fluid can be passed through one or more ultrafilters(described below) to ensure the dialysate fluid meets certain regulatorylimits for microbial and endotoxin contaminants.

Dialysis can be performed in the dialysis delivery system 104 of thedialysis system 100 by passing a user's blood and dialysate throughdialyzer 126. The dialysis system 100 can include an electroniccontroller configured to manage various flow control devices andfeatures for regulating the flow of dialysate and blood to and from thedialyzer in order to achieve different types of dialysis, includinghemodialysis, ultrafiltration, and hemodiafiltration.

FIG. 4 shows one example of front panel 210 of the dialysis deliverysystem 104 of FIG. 3, which can include a number of features that assistwith positioning and attaching cartridge 120 and its associated tubingset to the dialysis system 100, and for monitoring and controlling fluidflow along the tubing set of the cartridge. During installation of a newsterile cartridge onto the dialysis system, alignment features on thecartridge (e.g., holes 125 through the cartridge, shown in FIG. 5) canbe lined up with locator pegs 260. The locator pegs also serve to alignthe cartridge and the tubing set with features on the front panel usedfor dialysis treatment, including blood pump 213 and spring wire 22,positioning features 212, venous and arterial pressure sensor(s) 182 aand 182 b, venous air sensor 2161, arterial air sensor 216, pinchclamp(s) 180 a-d, and venous drip chamber holder 179. Blood pump 213 canbe a peristaltic pump, for example. A holder or slot 215 for a heparinpump or syringe is also shown.

The cartridge can be pressed into place on the front panel using theselocator pegs 260 to ensure that all the features of the cartridge andtubing set line up and are installed properly with the correspondingfeatures of the front panel 210. In some embodiments, the cartridge canbe easily installed with a single hand, and closing the door of thesystem can seat the cartridge onto the system. As shown in FIG. 1, thedialysis system can include wheels for ease of transport. In onespecific embodiment, a force applied to seat the cartridge horizontallyonto the front panel 210 by closing the door with a downward rotatingmotion of a lever on the door does not tend to move the dialysis system100 on its wheels.

The pinch clamps can be used for a number of functions before, during,and after dialysis therapy. The pinch clamps 180 a-d can be controlledby the electronic controller of the dialysis delivery system. Pinchclamps 180 a and 180 b can be configured to control the flow of salinefrom a saline source (such as a saline bag) to the tubing set. In someembodiments, the pinch clamps can be opened and the blood pump 213 canbe operated to draw saline into the tubing set to remove air during apriming sequence, to flush impurities from the dialyzer beforetreatment, and to displace blood back to the user at the end of atreatment. The pinch clamps 180 a and 180 b can also be used to delivertherapeutic boluses of saline to the user during therapy to maintainblood pressure or adjust electrolytes or fluid levels of the patient. Inother embodiments, pumps such as peristaltic pumps may be configured todeliver therapeutic boluses of saline to the user.

Pinch clamps 180 c and 180 d can be configured to close the arterial andvenous lines of the tubing set that connect to the user. They can alsobe opened and closed multiple times before, during, and after treatmentto facilitate actions such as tubing set priming, discarding of primingsaline, blood return to the patient, and/or draining the dialyzer aftertreatment. In one embodiment, the system can incorporate informationfrom venous air sensor 2161, arterial air sensor 216, or other airsensors in the system to close pinch clamps 180 c and 180 d in the eventthat air bubbles are found in the lines, particularly in the venousline. In a further embodiment, the system can be configured to removethe detected air bubble(s) by reversing the operation of the blood pumpto attempt to clear the air bubble(s) through the venous drip chamber.

Pinch clamps 180 a-d can also be actuated to perform a series ofself-tests on the tubing set prior to each treatment. The tubing set canbe pressurized with the blood pump, and the pressure can be held in thetubing set by closing the pinch valves. The arterial and venous pressuresensors can then be used to look for pressure decay in the tubing set.

FIG. 4 also illustrates venous drip chamber holder 179, which caninclude a pair of venous level sensors 181 a and 181 b. When thecartridge is coupled to the dialysis delivery system, the venous dripchamber (described in more detail below) can engage the venous dripchamber holder 179. During dialysis therapy, the venous level sensors181 a and 181 b can monitor the fluid level in the venous drip chamber.If the fluid level rises above sensor 181 a, then the dialysis deliverysystem can automatically pump air into the venous drip chamber to lowerthe fluid level. Alternatively, if the fluid level dips below sensor 181b, then the dialysis delivery system can automatically pump air out ofthe venous drip chamber (or alternatively, vent air out of the chamber)to raise the fluid level. In other embodiments, the system may comprisea single analog or non-binary digital level sensor in the place of thetwo venous level sensors to detect the actual level within the dripchamber. The dialysis delivery system can then be configured to performanalogous adjustments as described above based on the level detected bythis single sensor. The single sensor can comprise, for example, anultrasonic, optical, or capacitive level sensor.

Still referring to FIG. 4, in one embodiment, attaching the cartridgeonto the front panel 210 properly will engage cartridge presencedetector 214, which can be a switch or a sensor configured tocommunicate to the dialysis system (e.g., to a controller of the system)that a cartridge is installed on the front panel. As a safetyprecaution, the system will not allow pinch clamps 180 a-d to be closeduntil the cartridge presence detector 214 indicates that the cartridgeis installed properly. The presence detector can also initiate automaticloading of a blood pump portion of the tubing set into the blood pump.In one embodiment, the blood pump can include a spring wire 22 that isactuated to grasp and pull the blood pump portion of the tubing set intothe blood pump when the presence detector 214 is depressed. Furthermore,the connection of the cartridge and tubing set to the front panel canalso initiate a self-check in each portion of the tubing set to identifyany leaks in the tubing.

FIGS. 5 and 6 illustrate one embodiment of a cartridge 120 includingtubing set 122 attached to an organizer 124. Although the majority ofthe tubing set 122 is blocked from view in FIG. 5 by the organizer,arterial line 230, venous line 232, saline line 233, and heparin line234 can be seen. Referring to FIG. 5, a user can ensure proper placementof the cartridge relative to the front panel with organizer 124 byaligning holes 125 of the organizer with the locator pegs 260 of thefront panel. FIG. 5 shows a plurality of aligning holes 125 near the topof the organizer, but it should be understood that any number andlocation of aligning holes and locator pegs can be used to align andmount the cartridge 120. In addition, the organizer 124 can ensureproper placement of the tubing set 122 relative to one or more featuresof the dialysis system, including valves (such as pinch valves 180 a-ddescribed above), sensors (such as pressure and air sensors) the bloodpump, the venous drip chamber, etc. Also shown in FIG. 5, the cartridgecan include a number of access holes 2165 for gaining access to featureson the dialysis delivery system, such as gaining access to pinch valvesor the blood pump when the cartridge is installed on the system.

FIG. 6 shows the back side of the cartridge 120 and organizer 124 whichis configured to interface with the front panel 210 of the dialysisdelivery system, including the tubing set 122. The tubing set 122 of thecartridge 120 can include an arterial line 230, a venous line 232, and ablood pump portion 2167 configured to interface with the blood pump 213on the front panel 210. The blood pump 213 can be configured to drawblood from a user through arterial line 230, pass the blood through adialyzer, and return the treated blood to the patient through venousline 232. The tubing set 122 can also be connected to venous dripchamber 361 for the removal of air from the lines during therapy andpriming. A continuous pathway through which blood can circulate anddialyze can be created by connecting one end of the arterial line 230and one end of the venous line 232 of the tubing set 122 to the user'sblood vessels, such as via an access point (e.g., fistula needles orcatheter). Opposite ends of the arterial and venous lines can beattached to the dialyzer (described below), such as via color codedconnectors (e.g., red for arterial and blue for venous).

The tubing set can further include saline connections 353 a and 353 b toa saline solution, such as a saline bag, via a saline line 233. As shownin FIG. 6, saline connection 353 a can connect to the tubing setproximal to the blood pump portion of the tubing set. Tubing set 353 bcan exit the cartridge and connect to the tubing set on arterial line230 near where the arterial line is connected to the user. Connectingthe saline connection 353 b near the arterial connection to the userimproves blood return after a dialysis treatment since all the blood inthe arterial line can be flushed back into the user. The tubing set canalso include a connection to a heparin pump or syringe via the heparinline 234. The heparin pump and heparin line can connect to the tubingset at a non-pulsatile location, such as at the top of the venous dripchamber, to prevent back-streaming of blood up into the heparin line.The connection at the top of the venous drip chamber can be anon-pulsatile location due to the air gap created between the heparinline and fluid in the venous drip chamber.

Flow of fluid, such as blood, through the tubing set 122 will now bedescribed. As described above, the blood pump that interacts with bloodpump portion 2167 of tubing set 122 can be a peristaltic pump. The bloodpump can operate in two modes of operation. One mode of operation can bea “forward” operating mode of the blood pump that can be used duringdialysis therapy to move blood from the patient into the tubing set andback to the patient. Another mode of operation can be a “reverse”operating mode of the blood pump that can be used during a primingsequence to move saline through the tubing set. Fluid flows through thetubing set in the “forward” operating mode in a direction opposite tofluid flowing through the tubing set in the “reverse” operating mode.During dialysis therapy, blood can be drawn from the patient into thetubing set 122 through arterial line 230, due to the blood pump 213interacting with the tubing set in the “forward” operating mode.Arterial pressure pod 355 can mate with a pressure sensor (arterialpressure sensor 182 b of FIG. 4) or transducer on the front panel of thedialysis delivery system to measure the pressure on the arterial lineduring therapy. The arterial pressure pod 355 comprises a diaphragm thatallows for pressure to be transmitted without the transmission of bloodinto the system. The blood can continue through the tubing set, pastsaline connection 353 a and through the blood pump portion of the tubingset, and through tubing portion 357 towards the dialyzer. Once the bloodhas traveled through the dialyzer, it can continue in the tubing set 122through tubing portion 359 back into the cartridge, where it entersvenous drip chamber 361 at the bottom of the drip chamber at entry port365. Blood flows into the venous drip chamber 361, where air isseparated from the blood into the venous drip chamber and removed fromthe system (e.g., such as from a vent or port at the top of the dripchamber). The venous drip chamber can be connected to a venous pressuresensor or transducer on the dialysis delivery system via line 363 andvenous transducer protector 371, which prevents blood or other fluidsfrom contaminating the pressure sensor. Blood that has entered thevenous drip chamber can then exit the chamber via exit port 367 andcontinue to flow through the tubing set until it is returned to thepatient through venous line 232.

As shown in FIG. 6, the venous drip chamber includes entry and exitports 365 and 367 that allows blood to enter and exit the venous dripchamber from the bottom of the venous drip chamber. Any air bubblescaught in the line or the blood percolate into the chamber and areremoved from the blood before it is returned to the patient. Thisconfiguration allows for fluid flow through the tubing set to bereversed during priming of the dialyzer to push air up and out of thedialyzer. It also allows for the flow of blood to be reversed in thetubing set in the event that air is detected in the venous line of thetubing set.

Before treatment, the tubing set can be primed with saline to remove airfrom the line and prepare the system for dialysis therapy. During apriming sequence, the arterial and venous lines of the tubing set can beconnected together to form a continuous loop in the tubing set. FIG. 18shows one embodiment of a union joint 256 configured to attach arterialline 230 to venous line 232.

Saline can be drawn into the tubing set through saline connections 353 aand/or 353 b by activating the blood pump in the “forward” and “reverse”operating modes to cause the blood pump to interact with the tubing setand move saline into the tubing set from the saline source. When thepump operates in this “reverse” operating mode, the saline moves fromthe saline source into the tubing set and the blood-side of the dialyzerto fill the tubing set and the dialyzer with fluid and remove air fromthe tubing set via the venous drip chamber. In this “reverse” operatingmode, saline flows through the tubing set in the opposite direction ofblood flow during dialysis therapy. Thus, the saline flows through thevenous drip chamber before flowing through the blood-side of thedialyzer. Air in the venous drip chamber can be monitored with thevenous level sensors. Any air in the system can be pushed by the salineinto the venous drip chamber.

When the venous level sensors no longer detect any changes to the fluidlevel in the venous drip chamber, or when air sensors no longer detectair circulating through the tubing set, then the tubing set is primedand ready for treatment. The blood pump can then be operated in the“forward” operating mode to move the saline in the other direction thandescribed above and out of the tubing set. In the “forward” operatingmode, the saline travels through the blood-side of the dialyzer beforepassing through the venous drip chamber and into the patient throughvenous line 232. In some embodiments, the saline used during the primingsequence is delivered into the patient at the start of dialysis therapy.The amount of saline delivered is tracked and accounted for duringdialysis therapy depending on the patient's individual fluid removalrequirements. In another embodiment, some or all of the saline is pumpedor drained out of the tubing set prior to therapy.

To complete the priming sequence, dialysate can be pumped or movedthrough the dialysate-side of the dialyzer with a dialysate pump(described below). The dialysate is pumped through the dialysate-side ofthe dialyzer in the same direction that saline is pumped through theblood-side of the dialyzer. The direction of the saline and dialysatethrough the dialyzer can be in the direction of bottom to top throughthe dialyzer, which allows the bubbles to naturally purge through thetop of the dialyzer. Thus, the priming sequence of the presentdisclosure can remove air from both the blood-side and dialysate-sidesof the dialyzer without physically manipulating or “flipping” anorientation of the dialyzer, as is required by other conventionalsystems, since the priming sequence moves fluid through both sides ofthe dialyzer in the same direction.

During therapy, blood in the tubing set normally passes through theblood-side of the dialyzer in the top down direction. However, duringpriming, the blood pump can be operated in the “reverse” direction topush saline through the dialyzer in the bottom to top direction to moreeffectively remove air from the dialyzer. The unique configuration ofthe tubing set and venous drip chamber allows for the flow of saline inthe “reverse” direction through the tubing set because fluid both entersand exits the venous drip chamber at connections on the bottom of thevenous drip chamber. Conventional venous drip chambers, in which tubingconnections are made at the top and bottom of the venous drip chamber,only allow for fluid flow through the venous drip chamber in onedirection. The unique configuration of this disclosure allows forpriming of both the blood and dialysate sides of the dialyzer withouthaving to physically flip the dialyzer. Any air generated in the venousdrip chamber during priming can be removed by either venting out of thesystem, or pumping out of the system. In one embodiment, the pinchvalves of the system can be periodically actuated to open and close thesaline lines of the tubing set depending on the timing of the primingsequence to “bang” bubbles loose in the dialyzer. For example, the pinchvalves can be opened and closed every 4-8 seconds to create a pulsingeffect of the saline in the lines.

After a priming sequence when saline is in the tubing set, the systemcan further run self-tests to check for leaks in the tubing set. In oneembodiment, the pinch valve on the venous line can be closed with theblood pump running, and air can be pumped into the venous drip chamber.Next, the arterial pinch valve can be closed, and the venous pinch valvecan be opened, and the system can check for pressure stabilization. Ifthere is no pressure decay, it can be confirmed that there are no leaksin the system.

At the completion of a dialysis treatment, blood still remains insidethe tubing set. The blood pump 213 can be controlled to draw saline intothe tubing set to push the remaining blood back into the patient. Thisblood return mechanism can be highly controlled by the controller andblood pump of the system. For example, during dialysis therapy and bloodreturn, the controller of the system can monitor and track the exactnumber of revolutions made by the blood pump when the pinch valves thatcontrol saline administration are open to know exactly how much salinehas been pushed into the tubing set. The blood pump can then be stoppedor de-activated when the desired volume of saline is drawn into thetubing set. This allows the system to know exactly how much saline hasbeen used, and how much remains in the saline source or bag. At the endof the dialysis therapy, the amount of blood in the tubing set is known(typically around 250 ml), so the system can precisely meter the correctamount of saline into the tubing set to push the blood back into theuser. The anticipated amount of saline to use for blood return(typically 300-600 ml depending on the varying degree of thoroughness ofthe blood return) can be integrated into the overall fluid removaltarget for ultrafiltration so that after the blood return the patienttarget weight is attained. If the needed amount of saline does notremain in the saline source prior to blood return, the system can alertthe user that the saline source needs to be refilled or replaced.

In one embodiment, the dialyzer can be flushed prior to beginningdialysis therapy with a patient. In some cases, clinics ignore thislabeling and do not flush the dialyzer. The system can be configured toflush the dialyzer with up to 500 ml of saline. As described above, thetubing set is filled with saline during the priming sequence. Duringthis priming, the arterial and venous lines are attached to each otherwith union joint 256 as illustrated in FIG. 18. After the tubing set isprimed, the patient can remove cap 258 from the union joint 256 andposition the union joint over a waste bucket. The dialysis system canthen be placed into a prime discard sequence, which first confirms thatvalves 180 b and 180 c (from FIG. 17) are closed, and that valves 180 aand 180 d (from FIG. 17) are open. The blood pump can be operated in aforward direction to draw saline into the tubing set until the desiredprime discard amount is pumped through the system and drained though theunion joint 256 of FIG. 18. Next, valve 180 d is closed, valve 180C isopened, and the saline is allowed to be gravity drained through theunion joint until the proper amount of saline feeds out of the unionjoint (e.g., 40 ml of saline in one embodiment).

The system can also automatically drain any fluid out of the dialyzerafter a dialysis treatment. In one embodiment, the blood pump can be runin the reverse direction with the venous line clamped to pull fluid fromthe dialysate chamber of the dialyzer through the dialyzer microtubewalls against gravity through the dialyzer and into the saline source orbag.

FIG. 7 shows a flow diagram of the water purification system 102contained within the dialysis system 100. Incoming water, such as fromthe tap, can flow through a number of filters, including one or moresediment filters 108 and one or more carbon filters 110. A chlorinesample port 195 can be placed between the carbon filters 110 to providesamples of the fluid for measuring chlorine content. Redundant or dualcarbon filters can be used to protect the system and the user in theevent of a carbon filter failure. The water can then pass through areverse osmosis (RO) feed heater 140, a RO feed pump 142, one or more ROfilters 112 (shown as RO1 and RO2), and a heat exchanger (HEX) 144.Permeate from the RO filters 112 can be delivered to the HEX 144, whileexcess permeate can be passively recirculated to pass through the ROfeed pump and RO filters again. The recirculation helps with operatingof the water purification system by diluting the incoming tap water withRO water to achieve higher rejection of salts from incoming water. Afterpassing through the HEX 144, the purified water can be sent to thedialysis delivery system 104 for preparing dialysate and assisting withdialysis treatments. Additionally, concentrate from the RO filtersduring the water purification process can be sent to drain 152.

Referring to FIG. 8, the water purification system 102 of the dialysissystem can include one or more subsystems as described above in FIG. 7,including a water supply subsystem 150, a filtration subsystem 154, apre-heating subsystem 156, an RO filtration subsystem 158, and apasteurization subsystem 160. Each of the subsystems above can produceoutput to a drain 152. The water purification system 102 can beconfigured to purify a water source in real-time for dialysis therapy.For example, the water purification system can be connected to aresidential water source (e.g., tap water) and prepare pasteurized waterin real-time. The pasteurized water can then be used for dialysistherapy (e.g., with the dialysis delivery system) without the need toheat and cool large batched quantities of water typically associatedwith water purification methodologies.

FIG. 9 shows the features of the water supply subsystem 150 of the waterpurification system, which can include a variety of valves (e.g.,three-way valves, control valves, etc.) for controlling fluid flowthrough the water purification system. For example, at least one valve2169 can be opened to allow water to flow into the water purificationsystem for purification. The incoming water can flow in from a tap watersource 2171, for example. Fluid returning from the water purificationsystem can be directed to drain 152 through one or more of the valves.Furthermore, the subsystem can include a supply regulator 183 that canadjust the water supply pressure to a set value. A drain pressure sensor153 can measure the pressure at the drain. Water can flow from the watersupply subsystem 150 on to the filtration subsystem, described next.

FIG. 10 shows one embodiment of a filtration subsystem 154 of the waterpurification system. The filtration subsystem can receive water from thewater supply subsystem 150 described in FIG. 9. Water can first passthrough a supply pressure sensor 2173 configured to measure the waterpressure and a supply temperature sensor 2175 configured to sense thetemperature of the incoming water supply. The filtration subsystem caninclude a sediment filter 155, for example, a 5-micron polypropylenecartridge filter. The filter typically requires replacement every 6months. Based on the high capacity of the sediment filter and therelatively low flow rate through the filter, the life expectancy isestimated to be over 1 year based on the average municipal water qualityin the US. A replacement interval of 6 months provides high assurancethat premature sediment filter fouling should be rare. Also, expected tobe a rare occurrence based on the construction and materials of thefilter is a failure that results in unfiltered water passing through thefilter. A post-sediment pressure sensor 2177 can measure the pressuredrop across the sediment filter to monitor and identify when thesediment filter needs to be replaced. Should the sediment filter allowunfiltered water to pass the result would be fouling of the carbonfilters which would be detected by a pressure drop at post-sedimentpressure sensor 2177. If this pressure drop is the significant factorwhen the sensor drops to 5 psig, the system will require replacement ofboth the carbon filters and the sediment filters prior to initiatingtherapy.

The water can then flow through one or more carbon filters 110 (shown asCF-1 and CF-2) configured to filter materials such as organic chemicals,chlorine, and chloramines from the water. For example, the carbonfilters 110 can include granulated carbon block cartridges having10-micron filters. The carbon filters can be connected in series with achlorine sample port 195 positioned in the flow path between the carbonfilters. The chlorine sample port can provide a user with access (suchas through the front panel of the system) to the flowing water such asfor quality control purposes to ensure the total chlorine concentrationlevel of the water is below a certain threshold (e.g., below 0.1 ppm).Additionally, a post-carbon pressure sensor 2179 can be placed after thecarbon filter(s) to monitor the fluid pressure in the line after thesediment and carbon filtration. As is also shown in FIG. 10, an optionalair separator 187 can be placed between the sediment filter and thecarbon filter(s) to remove excess air and bubbles from the line. In someembodiments, each carbon filter can specified to have a service life of2500 gallons producing water that has less than 0.5 ppm of free chlorineand chloramine when operating in high chlorine conditions and at ahigher flow rate than the instrument supports so an expected life ofgreater than 2500 gallons is expected. Based on a maximum treatment flowrate of 400 mL/min through the carbon filters the expected for a singlecarbon filter is approximately 6 months to a year or more depending onincoming water quality. The system typically requires replacement ofboth filters every 6 months. Most carbon filters cannot tolerate heat orchemical disinfection, therefore a recirculation/disinfection fluidpath, implemented by the water supply and drain systems, does notinclude the carbon filters (or the sediment filters). Since the chlorineabsorption capacity of carbon filters is finite and dependent on theincoming water quality, a water sample from the chlorine sample port 195can be taken to verify that the water has a free chlorine concentrationlevel of less than 0.1 ppm. Using the two stage carbon filtration andverifying the “equivalent absence” of free chlorine after the firstcarbon filter ensures that the second carbon filter remains at fullcapacity in complete redundancy to the first. When the first carbonfilter does expire, both filters are typically replaced. Water can flowfrom the filtration subsystem to the pre-heating subsystem, describednext.

FIG. 11 shows one embodiment of a pre-heating subsystem 156 of the waterpurification system. The pre-heating subsystem can be configured tocontrol the temperature of water in the line to optimize RO filtrationperformance. The pre-heating subsystem can include one or more RO feedheaters 186, which can comprise, for example a thermoelectric devicesuch as a Peltier heater/cooler. The RO feed heater 186 can beconfigured to regulate or adjust the temperature of the water before ROfiltration. In one embodiment, the target temperature for reverseosmosis is 25 degrees C. for optimal RO filter performance. If the wateris too cold the RO filters will have insufficient flow and the systemwill not make enough water. If the water is too warm the RO filters willallow more flow but also have reduced salt rejection. In one embodiment,25° C. is the point at which flow and rejection are balanced to providesufficient water volume with adequate rejection. The RO feed heater canbe used to both heat or cool the fluid flowing through the heater. Forexample, in some embodiments, the RO feed heater can recover heat fromwaste water or used dialysate by way of the Peltier effect. In otherembodiments, such as during a heat disinfect cycle, the RO feed heatercan be placed in opposing polarity to negate Peltier effects. Duringwater treatment, the incoming water flows through a titanium plateattached to the hot side of two thermoelectric wafers of the RO feedheater. Waste water can be directed through a separate titanium plateattached to the cold side of the wafers. Heat is therefore pumped fromthe waste water to the incoming water via the Peltier effect. At maximumpower when the preheating system achieves a coefficient of performanceof two, meaning half of the power heating the incoming water isrecovered from waste water and the other half is from the electricalheating of the wafers. At lower power levels the coefficient ofperformance is higher meaning a higher percentage of the heat isrecovered from the waste stream. During heat disinfect thethermoelectric wafers of the RO feed heater can be placed in opposingpolarity. In this way both titanium plates are heated and the Peltiereffect is negated. This ensures that the water is heated only and isalways above the incoming temp on either side of the heater.

As shown in FIG. 11, the pre-heating subsystem 156 can include a processsupply valve 188 in the line between the filtration subsystem and the ROfeed heater, and a used dialysate return valve 190 for routing useddialysate to the drain. The RO feed heater can include a pair oftemperature sensors 192 and 194 to measure the temperature of the fluidon either side of the heater. Water can flow from the pre-heatingsubsystem to the RO filtration subsystem, described next.

FIG. 12 shows one embodiment of a RO filtration subsystem 158 of thewater purification system. The RO filtration subsystem can receivepre-heated water from the pre-heating subsystem described above. The ROfiltration subsystem can include a RO feed pump 142 that can drive wateracross one or more RO filters 112 (shown as RO-1 and RO-2) to produce apermeate flow and a concentrate flow. The concentrate flow can befiltered by more than one RO filter. In addition, the permeate flow canbe combined with excess permeate and be recirculated back to blend withincoming water. In addition, each RO filter 112 can include arecirculation pump 200 to keep fluidic line flow velocity high over theRO filters. The recirculation pumps can run at a constant velocity,driving any flow emanating from the concentrate flow back into the inletof the RO filters. Using a separate recirculation pump instead ofrecirculating through the RO feed pump lowers overall power consumptionand keeps flow velocity over the RO membranes high to reducing foulingand allow for high water production rates. In some embodiments, the ROfeed pump can be high pressure but relatively low flow pumps compared tothe recirculation pump(s), which can be low pressure but high flowpumps.

The pressure created by the RO feed pump and a RO concentrate flowrestrictor 2181 can control the flow rate of waste to the drain. Toensure that the restriction does not become fouled or plugged, the flowthrough the RO concentrate flow restrictor can be periodically reversedby actuating valves 180. In addition, to improve filter life andperformance, recirculation pumps can be used to increase fluid flow ratein the RO filter housings. This increase in flow rate can serve toreduce a boundary layer effect that can occur near the surface of ROfilters where water near the filter membrane may not flow. The boundarylayer can create an area with a higher concentration of total dissolvedsolids that can build up over the surface of the RO filter and maycollect and foul the RO filter.

The RO filtration subsystem can include on or more conductivity sensors196 configured to measure the conductivity of water flowing through thesubsystem to measure solute clearance, or per, pressure sensors 198configured to monitor fluid pressures, and air separators 187 configuredto separate and remove air and air bubbles from the fluid. Additionally,the RO filtration subsystem can include a variety of valves 180,including check valves, and fluid pumps for controlling flow through theRO filters and on to the pasteurization subsystem, back through the ROfiltration subsystem for further filtration, or to the drain. Water canflow from the RO filtration subsystem to the pasteurization subsystem,described next.

FIG. 13 illustrates one embodiment of a pasteurization subsystem 160 ofthe water preparation system. The pasteurization subsystem can beconfigured to minimize patient exposure to microbiological contaminationby heating the fluid to eliminate microbiological contamination andendotoxins from the system. The pasteurization subsystem can include aheat exchanger (HEX) 145 configured to heat water to pasteurizationtemperature, allow the water to dwell at the high temperature, and thencool the water back to a safe temperature for the creation of dialysate.

In some embodiments, the HEX 145 can heat water received by thepasteurization subsystem to a temperature of approximately 148 degreesCelsius. The heated water can be held in a dwell chamber of the HEX fora time period sufficient to eliminate and kill bacteria and denatureendotoxins. Endotoxins can be described as the carcasses of deadbacteria, characterized by long lipid chains. During water and dialysatepreparation, endotoxins can be monitored along with bacteria to judgethe purity of the dialysate. Endotoxins in dialysate can cause anundesirable inflammatory response in users. Therefore, it is desirableto minimize the levels of endotoxin in the dialysate. Endotoxins are notreadily trapped by the pore size of typical ultrafilters. Instead, theendotoxins are stopped by ultrafilters through surface adsorption whichcan become saturated with endotoxins to the point that additionalendotoxin will start to pass through. Heating endotoxins in superheatedwater to temperatures as low as 130 degrees C. have been demonstrated todenature endotoxins but the required dwell time is very long (manyminutes). At these elevated temperatures, where the water remains in theliquid phase, water which is typically considered a polar solvent andbegins to behave like a non-polar solvent to denature the lipid chainsof the endotoxin. As the temperature increases to 220 degrees C. orhigher, the denaturing of endotoxins occurs in seconds. The HEX of thepresent disclosure can run at 220 degrees C. or higher while maintaininga pressure (approximately 340 psi for 220 degrees C., but the HEX canwithstand pressures of over 1000 psi) that keeps the water in liquidform. In one embodiment, a preferred temperature and pressure range ofthe HEX is 180-220 degrees C. and 145-340 psi. The water can then becooled as it exits the dwell chamber. The HEX 145 is a self-containedcounterflow heat exchanger that simultaneously heats incoming water andcools outgoing water to reduce energy consumption.

The pasteurization subsystem can include a HEX pump 193 configured tomaintain a fluid pressure in the fluid line, to prevent the water fromboiling. After the water passes through the HEX 145, a water regulator197 can reduce the pressure of the water for use in the dialysisdelivery system. One or more pressure sensors 182 or temperature sensors184 can be included for measuring pressure and temperature,respectively, of the water flowing through the pasteurization subsystem.Furthermore, an air separator 187 can further remove air and air bubblesfrom the water. In one embodiment, a flow restrictor 189 and valve 180can be used to limit water dumped to the drain when the HEX 145 isheating up. Once the water has passed through the pasteurizationsubsystem, it has traveled through the entire water purification systemand is clean and pure enough to be used in dialysate preparation anddelivery by the dialysis delivery system.

FIG. 14 illustrates a schematic of a mixing subsystem 162 of thedialysis delivery system. Purified water from the water purificationsystem can be routed into the dialysis delivery system, where it canflow through heater 220 in preparation for final de-aeration inde-aeration chamber 221. In one embodiment, water flowing into theheater 220 can be approximately 43-47 degrees C., and the heater canheat the water up to 50 degrees C. or higher. The de-aeration chambercan be, for example, a spray chamber including a pump sprayer 222.During de-aeration, spray chamber recirculation pump 225 draws fluid ata high flow rate from the bottom of the de-aeration chamber. Heatedwater entering from the heater 220 then enters the de-aeration chamberabove the fluid level through a pump sprayer 222. The temperature of thewater as it enters and exits the heater can be monitored withtemperature sensors 184. This restrictive spray head in combination withthe high flow rate of the spray chamber recirculation pump 225 creates avacuum in the de-aeration chamber ranging from −7 psig to −11 psig. Thevacuum pressure and heat combine to effectively de-aerate the incomingwater. As air collects in the top of the de-aeration chamber and thewater level drops below level sensor 2183, the degas pump 191 can turnon or run faster to remove the collected air from the top of thede-aeration chamber. The degas pump 191 can remove a combination of airand liquid from the de-aeration chamber.

After de-aeration and subsequent cooling with the heater 220 toapproximately body temperature, acid and bicarbonate concentrates can bevolumetrically proportioned into the fluid path by way of concentratepumps 223 in order to reach the desired dialysate composition. The waterand concentrates can be mixed in a series of mixing chambers 224 thatutilize a time delay or volumetric mixing instead of in-line mixing tosmooth the introduction of fluids. FIG. 15 shows one embodiment of amixing chamber 224, which can include an inlet portion 236 a and anoutlet portion 236 b. The mixing chamber can include a plurality ofchannels 238 connecting the inlet portion to the outlet portion. Thechannels can be arranged so that some of the channels include longerpaths from the inlet portion to the outlet portion than other channels.Thus, fluid traveling through the channels of the mixing chamber can beseparated and divided along the varying channel lengths before beingrecombined to achieve more complete mixing of “lumpy” incoming fluid bythe time it exits the mixing chamber.

In one embodiment, the concentrate pumps can run at an elevated rate topush out any air bubbles in the pumping mechanism (e.g., can run atupwards of 30 ml/min compared to ˜7 ml/min during normal operation).Once the dialysate is mixed, a dialysate pump 226 can control the flowof dialysate through the dialysis delivery system. The mixing subsystem162 can include various pressure sensors 182, temperature sensors 184,and conductivity sensors 196 to monitor the fluid during the dialysatepreparation. The conductivity sensors can be used to measure the fluidionic properties to confirm that the composition is correct.

The flow path within the dialysate delivery system can include one ormore bypass or circulation routes that permit circulation of cleaningand/or sterilization fluid through the flow path. The circulation routemay be an open flow loop wherein fluid flowing through the circulationroute can be dischargeable from the system after use. In anotherembodiment, the circulation route may be a closed flow loop whereinfluid flowing through the circulation route is not dischargeable fromthe system.

FIG. 16 illustrates an ultrafiltration subsystem 164 of the dialysisdelivery system which can receive the prepared dialysate from the mixingsubsystem. The ultrafiltration subsystem is configured to receiveprepared dialysate from the mixing subsystem 162. Dialysate pump 226 andused dialysate pump 227 can be operated to control the flow of dialysatethrough the ultrafiltration subsystem. The pumps 226 and 227 can controlthe flow of dialysate to pass through an ultrafilter 228 and a dialysateheater 230 before entering dialyzer 126. Temperature sensors 184 canmeasure the temperature of the dialysate before and after passingthrough the dialysate heater 230. The dialysate heater can be userconfigurable to heat the dialysate based on the user's preference,typically between 35-39 degrees C. After passing through the dialyzer,the used dialysate can flow through a used dialysate pump 230 and backthrough the dialysate heater 228 before returning to drain. In oneembodiment, the degas pump from FIG. 14 can be used to wet the back ofthe used dialysate pump 227. The ultrafiltration subsystem can includeone or more actuators or valves 177 that can be controlled to allowdialysate to pass through the dialyzer 126, or alternatively, to preventdialysate from passing through the dialyzer in a “bypass mode”. Apressure sensor 182 c disposed between the dialysate pump 226 and theused dialysate pump 227 can be configured to measure a pressure of thedialysate between the pumps when dialysate is prevented from passingthrough the dialyzer in the “bypass mode”.

FIG. 17 illustrates a blood circuit subsystem 166 which is configured topull blood from the patient and create a flow of blood through thedialyzer during dialysis therapy to pass fluid from the blood-side ofthe dialyzer to the dialysate-side of the dialyzer or vice versa. Asdescribed above, the blood circuit subsystem 166 can include, amongother features described herein, the tubing set 122, blood pump 213,pinch clamps 180 a-d, venous drip chamber 361, venous level sensor(s)181, arterial line 230, and venous line 232, saline source 240, andheparin pump 242. The blood pump 213 can be controlled to operate infirst and second modes of operation. During dialysis therapy, the bloodpump 213 can be operated in a first operating mode in which the pumppulls blood from the patient through arterial line 230, flows throughthe tubing set in the direction of arrow 244, flows through the dialyzer126, flows through the venous drip chamber 361, and is returned to thepatient through venous line 232. The blood pump can also be operated ina second operating mode in which the pump direction is reversed to causefluid in the lines to flow in the direction of arrow 246 (for example,during a priming sequence as described above.

The blood circuit subsystem can also include a venting circuit 248adapted to automatically control the fluid level in venous level chamber361, as described above. The venting circuit can include a pressurecompensating pump 250, one or more venting valves 252, and an air filter254. The venous pressure sensor 182 a of the system can also be locatedin the venting circuit 248. During dialysis therapy, the venous levelsensor(s) 181 can monitor a fluid level of blood in the venous dripchamber 361. The electronic controller can receive the fluid levelinformation from the sensor(s) and automatically maintaining the fluidlevel of the blood in the venous drip chamber by pumping or venting airout of the venous drip chamber with pressure compensating pump 250and/or venting valves 252 if sensor(s) detect the fluid level droppingbelow a lower threshold, and by pumping air into the venous drip chamberif the sensor(s) detect the fluid level rising above an upper threshold.

Still referring to FIG. 17, a method of returning blood in the tubingset to the patient after dialysis therapy will be described. First, theuser can clamp the line on their arterial needle (not shown in diagram)at the point where the arterial line 230 enters their body. This clampcan be located in between saline connection 353 b and the user's body.The user can then confirm ACLMP is open, which is another clamp on thearterial line distal to the saline connection 353 b. Next, theelectronic controller of the dialysis system can open pinch clamps 180 band 180 c, and close pinch clamp 180 a. Next, the electronic controllercan direct blood pump 213 to operate in the “forward direction” to drawsaline from the saline source (e.g., a saline bag) into the arterialline 230 at saline connection 353 b through pinch clamp 180 b, which isvery close to where the arterial line connects to the patient. The bloodpump can operate for a specified time, or can run until a predeterminedvolume of saline (e.g., 300-600 ml) is drawn into the tubing set, toreturn the blood in the tubing set and dialyzer into the patient throughvenous line 232. In some embodiments, the blood return process can bemanually stopped based on the color of the saline in the tubing set(i.e., stopping the blood pump when the color of the saline becomesclear or a light-pink color).

The dialysate pump and used dialysate pump described above can be partof an electronic circuit in communication with the electronic controllerof the dialysis system to achieve a controlled ultrafiltration rate, andcan also be adjusted to precisely control the addition or removal offluid to or from the patient.

The dialysate pump and used dialysate pump can be controlled with a highdegree of precision to achieve dynamic balancing, periodic balancing,and continuous correction. Referring to FIGS. 16-17, dialysate pump 226and used dialysate pump 227 can be configured to pump dialysate throughthe dialysis delivery system. The dialysate pump can be controlled topush the dialysate through the ultrafilter and the dialysate heater toget heated.

To calibrate the flow of the system, the system can be controlled toenter a bypass mode in which valves 177 are actuated to preventdialysate flow through the dialyzer. This isolates the patient tubingset on the blood side of the dialyzer from the dialysate flow andcreates a closed system for dialysate flow that will not allowultrafiltration. Whenever the system is in bypass the used dialysatepump can be servoed to maintain constant pressure as measured bypressure sensor 182 c, which is positioned between the dialysate pump226 and used dialysate pump 227. The pump speed of the used dialysatecan be adjusted while the pump speed of the dialysate pump is maintainedat a constant speed until the pressure measured by pressure sensor 182 cstabilizes. Once the pressure is stabilized, the pump speed of the useddialysate pump vs the pump speed of the dialysate pump can be recordedas the pump speed ratio that results in zero ultrafiltration. When thesystems exits bypass and returns to dialysis therapy, the used dialysatepump speed can be adjusted based on the desired ultrafiltration rate.

When dialyzer is bypassed, pressure measurements of the dialysate can bemade independent of influences or pressures from the blood-side of thedialyzer (e.g., isolated from the blood tubing set). When the dialysateand used dialysate pumps operate at the same rate there is no pressurechange at pressure sensor 182 c positioned between the two pumps, sothere is no flow imbalance between the pumps. However, if the dialysateand used dialysate pumps operate at different rates then a flowimbalance is created between the pumps, and a pressure changerepresenting this flow imbalance can be measured at pressure sensor 182c. In some embodiments, the flow imbalance can be controlled based onthe pump strokes of the respective pumps. In other embodiments, the flowimbalance can be controlled based on lookup tables that determine theoptimal pump speeds based on the measured venous pressure. Theelectronic controller of the system can be configured to automaticallycontrol the flow of fluid across the dialyzer (i.e., ultrafiltration) byadjusting a pump speed of the used dialysate pump 227 with respect todialysate pump 226 (or alternatively, of the dialysate pump 226 withrespect to used dialysate pump 227) to create a flow imbalance betweenthe dialysate-side and blood-side of the dialyzer. When a flow imbalanceis created on the dialysate-side of the dialyzer by operating the pumps226 and 227 at different speeds, then fluid can flow across the dialyzermembranes from the blood-side to the dialysate-side, and vice versa, toequalize that flow imbalance.

The pump speeds of the dialysate pump 226 and used dialysate pump 227can be locked in by the system based on a desired rate ofultrafiltration, and valve 180 can be opened for normal operation duringdialysis therapy. During therapy, the system can continue to monitorvenous pressure on user side at pressure sensor 182 a. If the venouspressure changes (e.g., greater than 30 mm-Hg mercury in change), thesystem can be configured to automatically rebalance the pumps with thesame technique described above. This allows the pumps to be balanced toachieve the desired amount of fluid transfer through the dialyzer, oralternatively, to achieve no fluid transfer through the dialyzer. In onespecific embodiment, the system can detect changes in the venouspressure of the user and automatically adjust the speed of the useddialysate pump 227 based on a look-up table of speeds against venouspressure to maintain ultrafiltration balance in the user. Once thesystem has been calibrated, the used dialysate pump speed can bemodulated to adjust the rate of fluid removal from the patient. In someembodiments, a pump speed of the used dialysate pump can bealternatively increased or decreased relative to the dialysate pump toenable hemodiafiltration (e.g., pushing/pulling fluid onto the patient).

As described above, the water purification system and the dialysatedelivery system can both include a variety of pumps, valves, sensors,air separators, air sensors, heat exchangers, and other safety features.All of these features can be controlled electronically and automaticallyby the electronic controller of the dialysis system.

What is claimed is:
 1. A method of returning blood in a patient tubingset of a dialysis delivery system to a patient after a dialysistreatment, comprising: activating a blood pump coupled to the patienttubing set to draw saline into the patient tubing set and push bloodback into the patient; tracking a number of revolutions of the bloodpump to determine a volume of saline drawn into the patient tubing set;and de-activating the blood pump when a predetermined volume of salineis drawn into the patient tubing set.
 2. The method of claim 1 whereinthe predetermined volume comprises 300-500 ml.
 3. The method of claim 1,further comprising opening one or more pinch valves of the dialysisdelivery system to create a pathway between a saline source and thetubing set.
 4. The method of claim 3, further comprising opening one ormore pinch valves to create the pathway between the saline source andthe tubing set at or adjacent to a patient arterial access site.
 5. Themethod of claim 1, wherein blood is pushed back into the patient througha patient venous access site.
 6. The method of claim 1, wherein thepredetermined volume of saline is integrated into a fluid removal targetfor ultrafiltration during the dialysis treatment so a target weight ofthe patient is attained after returning the blood in the tubing set tothe patient.